Physicists create 'negative mass'???

[Topper]

https://phys.org/news/2017-04-physicists-negative-mass.html
How crazy and seriously is that?
May this be the material from which dark energy is made from?

 

[Kyle]

Push it, and unlike every physical object in the world we know, it doesn't accelerate in the direction it was pushed. It accelerates backwards.

What

 

[Artlav]

The full article is not accessible by any means i'm familiar with, but the abstract suggests that it's, for lack of a better word, a virtual phenomenon.

Basically, they poked at Bose-Einstein condensate, and got it to behave as if it had negative mass.

What it reminds me of is negative electrical resistance found in things like gas discharges and some active systems.
While not physically possible in general, it can happen within certain regions - it's not literally a thing having a negative resistance, but a system behaving as if it had one.

TL;DR: Might be something curious, might be boring - no way to tell without more details (and maybe much more research).

 

[Quick_Nick]

Another clickbaity butchering of a sci-fi buzzword.

 

[Thorsten]

Read the abstract of the original article once, and it sounds less spectacular already.

A negative effective mass can be realized in quantum systems by engineering the dispersion relation. A powerful method is provided by spin-orbit coupling, which is currently at the center of intense research efforts.

So this isn't a rest mass (which would be spectacular, because superluminal motion and causality violation), it's not even a mass of something concrete particle, it's a negative region in the dispersion relation of a collective phenomenon.

Which means there isn't really material 'stuff' that moves against an accelerating force - some excitation modes (wave packets) at a certain narrow wavelength region do (that's what dispersion relation means).

What happens is a bit similar to superconductivity, in that there light gets a weird dispersion relation in which you can suddenly assign a mass to light, which leads to a finite penetration depth of electromagnetic fields into superconducting matter.

So it is a weird and interesting phenomenon, but it's one in a looooong list of pretty strange dispersion relations observed in solid state physics and related areas.

 

[RisingFury]

Read the abstract of the original article once, and it sounds less spectacular already.

Oh, it is spectacular! They're capable of manipulating atoms into states they really don't want to be in. It's just that no matter how spectacular science is, it never lives up to the headlines.

So this isn't a rest mass (which would be spectacular, because superluminal motion and causality violation),

No, negative mass does not give you speeds faster than the speed of light. Complex, imaginary mass gives you that. Negative mass particles would still be restricted to below the speed of light, assuming that relativity holds for them.

 

[Urwumpe]

No, negative mass does not give you speeds faster than the speed of light. Complex, imaginary mass gives you that. Negative mass particles would still be restricted to below the speed of light, assuming that relativity holds for them.

Well, if you have enough negative mass and positive mass around, you could create an Alcubierre drive... :lol:

 

[Thorsten]

No, negative mass does not give you speeds faster than the speed of light

You are right of course - it seems I mixed it up with time arrow reversal.

---------- Post added at 08:38 AM ---------- Previous post was at 08:36 AM ----------

They're capable of manipulating atoms into states they really don't want to be in.

Every lamp does that (excitation of atoms into higher states they don't want to be in, de-excitation into the ground state by photon emission,...)

 

[RisingFury]

Every lamp does that (excitation of atoms into higher states they don't want to be in, de-excitation into the ground state by photon emission,...)

I'd say this one is a little bit more difficult